A device is already known from the state of the art for air conditioning a compartment, comprising a heat pump circuit. Said heat pump circuit traditionally comprises a first heat exchanger with the air in the compartment, a compressor, a second heat exchanger with the outside air, and an expander, all arranged in series in a closed circuit to form a loop.
A refrigerant flows in that heat pump circuit and exchanges heat, on the one hand in the first heat exchanger, and on the other hand with the outside air in the second heat exchanger.
In order to allow an optimal heat exchange, each exchanger comprises fins increasing the air exchange surface.
Under certain climate conditions, the humidity contained in the outside air can be deposited on the fins of the second heat exchanger in the form of frost. That frost fills the spaces between the fins, then covers the second heat exchanger with a layer of frost that may hinder the passage of air. In that case, the performance of the heat pump circuit decreases considerably.
One known solution to provide defrosting of the second heat exchanger consists of reversing the cycle of the heat pump, such that the refrigerant withdraws heat from the first heat exchanger, and gives heat to the second heat exchanger in order to melt the frost.
When such defrosting is done, the thermal comfort inside the compartment can decrease, since the heat pump circuit takes heat from the compartment by means of the first heat exchanger. Thus, in order to maintain a comfortable temperature in the passenger compartment, electric heating is generally activated to offset that heat withdrawal.
Such electric heating consumes quite a bit of energy, with the result that the solution is not very advantageous.
Other known solutions for defrosting the second heat exchanger are also known. For example, one known solution provides a heat storage reservoir connected to the heat pump circuit, designed to favor defrosting. In that case, heat is taken from the heat storage reservoir rather than the air in the compartment. However, the compartment is nevertheless heated very little during defrosting, which can cause a decrease in thermal comfort in compartment. Furthermore, such a device generally requires oversized components to have satisfactory operation. Thus, such a solution is also not very advantageous.